renamings/signature change

[Andre Poenitz]

I'd like to change the signature of

        DispatchResult
        InsetBase::dispatch(FuncRequest const & cmd, idx_type & idx, pos_type & pos);

        DispatchResult
        InsetBasse::priv_dispatch(FuncRequest const & cmd, idx_type & idx,
      pos_type & pos);


to 

        DispatchResult
        InsetBase::dispatch(FuncRequest const & cmd, CursorSlice & cur);

        DispatchResult
        InsetBasse::priv_dispatch(FuncRequest const & cmd, CursorSlice & cur);

The reason is that the current idx and pos _are_ parts of the same
CursorSlice anyway and the CursorSlice contains now texted's paragraph
offset member and I don't want to add a third reference argument.

This is not a difficult change but a large patch so I thought I better
ask.

Andre'